Variable pitch airplane propeller



April 23, 1940. w. s. TABER VARIABLE PITCH AIRPLANE YROPELLER 4 Sheets-Sheet 1 Filed April 5, 1938 INVENTOP WALTER S. TABER 23, 1940. w. s. TABER VARIABLE PITCH AIRPLANE PROPELLER 4 Sheets-Sheet 2 'INVENTOI' Q BY WALTER 5. TABER ATTORN 23, 1940. w. s. TABER VARIAPLE PITCH AIRPLANE PRQPELLER Filed April 5, 1938 '4 Sheets-Sheet 4 w E m mm MA Mb 0M1 xno 5. l mN S: n9 E v@ mm mm hm mm WALTER 5 TABER 1 ATToRN Patented Apr. 23, 1940 UNITED STATES- PATENT on-"ice 6 Claims.

(Granted under the act at March a, 1883, as amended April so, 1928; 370 o. 6:757)

The present invention relates to variable pitch propellers andit has a particular relation to airplane propellers in which the pitch of the blades can be varied at will while the aircraft is in flight.

One of the objects of the invention is the provision of a propeller of the character described which embodies a hub having an axially arranged member rotatably niounted therein provided with a semi-spherical surface in which one or more coaxial helical threads orcam grooves having an equal pitch are formed for operative engagement with the root portions of one on more propeller blades rotatably mounted in the hub and by means of which the blades may be simultaneously i rotated to vary the pitch thereof the desired degree.

Another object of the invention is the provision of a variable pitch propeller in which the several blades may be adjusted to alter their pitch with exactitude and which will maintain their adjustment without additional locking means.

A further object of the invention is the provision of a propeller in which the several blades are staggered to offset axially with respect to one another so as to rotate in different spaced parallel planes, thus cutting through and exerting a propelling or impelling action against different bodies ,of the air, water or other fluid medium with which they are in contact.

With these and other objects in view, as well as other advantagesthat maybe incident to the use of the improvements, the invention consists in the parts and combinations thereof hereinafter set forth and claimed, and with the under- 35 standing that the several necessary elements con- I stituting the'same may be varied in proportion and arrangement without departing from the nature and scope of the invention, as defined in the appended claims.

' 40 In order to make the invention more clearly understood, there are shown in the accompanying drawings, means for carryifig theinvention into practical use, without limiting the improvements in their useful application to the particular con- 45 struction, which, for the purpose ofexplanation,

have been made the subject of illustration. In the accompanying drawings: Fig. 1 is a view partly in front elevation and partly in vertical transverse section taken sub- 50 stantially on line l-l of Fig. 2; 4

Fig. 2 is a vertical longitudinal sectional view taken on line 2-2 of Fig. 1; a

Fig. 3 is a view partly in front elevatiomand partly in vertical transverse section taken sub 55 stantially on line'33 of Fig. 4; and

Fig. 4 is a vertical longitudinal sectional view taken on line 4-4 of Fig. 3.

Referring to the drawings, and particularly to Figs. 1 and 2 thereof, an airplane propeller embodying the present invention, is shown as com-'- 8 prising a hub, indicated as an entirety at M, and which in turn comprises two hollowcomplementary rearward and forward members II and I2 respectively, secured together by bolts l3. The members II and I2 are formed with opposed 10 sleeves l4 and I5 having a scarf joint Is therebetween adapted to be mounted on the crank or drive shaft ll of an engine, not shown, The sleeve I4 is keyed to the shaft H by means of a plurality of splines 18 formed on the sleeve and on the shaft and is held in abutting engagement .with a shoulder IS 'on the shaft by a nut 20 which v is threaded onto the extreme forward end of the shaft I! for engagement with the forward member l2 of the hub.

The hub I0 is also provided with a plurality o radially extending sockets 21 each being formed by complementary portions 28 and 29 of the members II and i2. Mounted for rotation within each of the sockets is a sleeve 3| formed at its inner end with an annular flange 32 for engagement with a shoulder 33 formed adjacent to the inner terminus ofthe socket and with internal screw threads 34 for engagement by corresponding screw threads on the root portion 35 of a propeller blade. The outer end of the sleeve 3| is formed with a plurality of slits 36, to provide a plurality of contractable outwardly tapered fingers 31 each of which is formed with inwardly extending projections 38.,,for engagement with notches 39 formed on the root 35 of the blade.-

These fingers are flexed inwardly so as to hold the projections 33 in interlocking engagement with the notches 39, by means of a frusto-conical nut\40 which is threaded onto the fingers 31 and 40 into abutting engagement with a shoulder 4| on the outer end of the socket 21. By means of this construction the sleeve 3i, root 35 and nut 40 rotate in unison but are prevented from radial dimlacement from the socket 21 by the flange 32 and nut 40. The sleeve 3| is also formed at its inner end with-an arm 42 which extends in a radial direction with respect to the, axis of rotation of the sleeve and whieh is formed at its outer end with segmental worm teeth, or gear 43, the r purpose of which will presently be described. I A spherical gear 44 is housed within the hub ill for intermeshing engagement with the segmental worm 43 and is formed with integral circumferential flanges 45 and 46 on each side F which are rotatably mounted on hearing rings 41 and 48 carried by the sleeve portions I4 and I5 of the hub Ill. The flange is formed with a worm gear for inter'meshing engagement with a worm 58 which isfixed to a shaft 5|. This shaft is journalled in bearings 52 and 53 mounted in an enlargement 54 formed on the inner portion II of the hub I8 and closed at its outer end by a screw plug 55. A worm gear 56 is fixed to the shaft SI and is driven by a worm 5'! fixed to a countershaft 58. This shaft is journalled in bearings 59 mounted in a transverse extension 68 of the enlargement 54 which is closed at its rear end by a screw plug 6|. shaft 58 is at times intermittently rotated, in order to adjust the pitch of the propeller blades, by means of a jaw clutch mechanism comprising a member 62 keyed to the shaft 58 and a member 63 freely mounted on the shaft 58 but held in driving engagement with the member 62 by a spring 64 interposed'between the member 63 and a nut 65 threaded onto the rear extremity of the shaft 58. A star wheel 66 is fixed to the clutch member '63 for engagement with upper.

and lower stops 61 and 68 formed on a vertical, reciprocable slide 69. This slide is suitably mounted on the engine frame and may be actuated by the pilot through the medium of a jointed rod or flexible cable connection, not shown.

Operation.-When the slide 69 occupies the intermediate position shown the star wheel 66 will pass between the steps 61 and 68 and no motion will be transmitted to'the associated reduction gearing and spherical gear 44, thus maintaining the propeller blades at a certain angle of pitch. If, however, the pilot should desire to vary the pitch of the propeller blades,

pitch of the propeller approaches a dangerous or undesired angle, the motion of the parts will automatically be arrested by the arms 42 engaging either of two stops 18 carried by the hub III, one on each side of the arms 42. When the .mechanismis thus locked against rotation,

breakage of the parts or stripping of the gears is prevented by the slipping of the'clutch mem-.

' bers 62 and 63 relative to one another.

-In Figs. 3 and 4 there is illustrated another form of the invention wherein the hub II comprises an outer substantially cylindrical portion 12 formed with a concentric'inner sleeve portion I3 adaptedto be keyed to the crank or drive shaft I4 of an engine; and forward portion I5 formed with an inner sleeve portion Iii-adapted to be screw threaded onto the forward end of J m factured and used by or for the Government of the drive shaft 14- and engaging the end of the sleeve portion 13 at a scarf joint 11. The portion I5 of the hub is also formed with an extreme forward cylindrical portion 18 for housing an electric motor 19 hereinafter to be described, and with a discoidal portion 88 adapted to be secured to the forward end of the portion I2 by bolts8I. A

The hub II is provided with a plurality of radially extending sockets 82, each being stag- The.

gered or offset in an axial direction with respect to one "another and within which the root portion 83 of a propeller-blade is rotatably mounted. The blades are each prevented from radial displacement by means ofa ring or collar 84 which is screw threaded-onto the inner extremity of the root 83 and which is formed withtwo annular shoulders 85 for abutting engagement with corresponding shoulders formed in the hub. A split 'frustoconical nut. 86 is screw threaded onto the socket 82 and is clamped thereon by bolts 81. These nuts form bearings for the blades within which they rotate when adjusted to vary their pitch. The collars 84 are-each formed with an arm 88 which extends in a radial direction with respect to its axis-of rotation and which has a stud 8'9 screw threaded intoits outer'extremity for engagement with a spiral cam, groove 90 formed in a spherical cam 9I. .T-he cams 9I- are preferably formed integrally with one another and are rotatably mounted upon the sleeve portions 13' and I6 of the hub in alinement with the sockets 82. The forward cam 9| is formed with an internal worm gear 92 which 'meshes with and -is driven by diametrically disposed pairs of worms 83. The'worms of each pair arefixed to the ends of a shaft 94 which is journalled in bearings 95 on the sleeve v portion 16 of the hub and which is rotated by a worm wheel 96 fixed thereto between the worms I 93. This worm wheel .is in turn driven by a worm 91 which is fixed to the rotor shaft 98 of the motor 19. The shaft 98 is journalled at its v rear end in a bearing 99 carried by the portion 16 of the hub and atits forward end in a bearing I68 carried by abracket I8I screw threaded onto the forward end 'of the cylindrical portion I8 of the hub. The stator of the motor 19 is carried by the portion 18 of the hub and is rotat-' ablebodily therewith, being prevented from displacement by screws I62. Thisportion of the mechanism is enclosed by a spinner or casing I03 which is fixed to the plate 80.

The motor I9 is preferably of the. synchronous reversible type energized by electric current I supplied through wires I84 connected with sliprings I85 mounted on the rear end of the member I3 of the hub and controlled from a dial-on the instrument'board. The control is such that when it is desired to turn the blades of the propeller to a certain pitch thedial is turned to a point indicating such pitch. This will cause the motor to rotate until it has turned the blades sufficiently and then automatically stop. The dial isprovided with limit switches which control. the range within which the blades may. be. turned. This automatic control may be of any well known type and therefore has not been explained in detail.

The mechanism hereinabove described may be modified in proportion and arrangement of the parts without departing from the nature and scope of the inventionas defined in the appended the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

-1. A variable pitch propeller comprising a hu a plurality of blades having their root portions mounted in said hub for rotation about radial y extending axes and in axially offset relation along said hub, a plurality of coaxially arranged one associated with each of said blades. an arm fixed to the root portion of each of said blades and extending partly around'the associated cam for operativeengagement therewith, and means for rotating said cams to rotate said arms and blades about said axes to vary the pitch of said blades.

2. A variable pitch propeller comprising a hub, a plurality of blades having their root portions mounted in said hub for rotation about radially extending axes: and in axially ofiset relation along said hub, a plurality of coaxially arranged spherical cams rotatably mounted in said hub, one associated with each of said blades, an arm fixed to the root portion of each of said blades duction gear train for rotating said .c

said hub, a plurality of coaxially arranged spher-' ical cams rotatably mounted in said hub, one,

associated'with each of saidblades, an arm fixed to the root portion of each of said blades and extending partly around the associated cam for operative engagement therewith, and an-e'lectric motorhoused within said hub for rotating said cams to rotate said arms and'blades about said axes to vary the pitch of said blades.

4. A'varlable pitch prop'eller comprising a hub, a plurality oi blades having their root portions mounted in saidhub for rotation about radially extending axes and in axially ofi'set relation along said hub, a plurality of coaxially arranged spherical cams rotatably mounted insaid hub, one assoclatedwltheachotsaidbladeaanarmfixed to the root portion of each of said blades and extending partly around the associatedcam for operative engagement therewith, an internal worm gear fixed to said cams, ellipsoida1 worms meshing with said worm gear at intervals there- 5 around, and means for rotating said 'ellip'soidaL worms to transmit rotary movement to said cams; and blades to vary the pitch of the latter;

5. A variable pitch propeller comprising a hub, a blade having its root portion mounted in said hub for rotation about a radially extending axis, a spherical worm'having threads of equal pitch extending substantially throughout its spherical surface rotatably mounted in said hub, an arm fixed to the root portion of said blade and having aworm gear segment thereon intermeshing with said spherical worm, an external worm gear fixed to said spherical worm coaxially thereof, a tangentially arrange a worm intermeshing with said worm gear for r tating the same and said spherical worm to rotate said arm and blade about said axis to vary the pitch of said blade, and means for "rotating said worm while the propellerisrotatin'g. p v

6. A variable pitch propeller comprising a hub, a blade having its root portion mounted in said hub for rotation about a radially extending axis, a spherical wormhaving threads of equal pitchextending substantially throughout its spherical surface rotatably mounted in 'said hub, an arm fixed to the'root portion of said blade and having a worm gear segment thereon intermeshing with said spherical worm. an external worm gear fixed to said spherical worm coaxially thereof, a tangentially arranged worm intermeshing with said worm gear for rotating the same and said spherical worm to rotate said arm and blade about 

